Wednesday, June 17, 2015

Lytro Camera (First Generation) Review

This is a review of the Lytro's First Generation camera, the first consumer light field camera that became famous for changing the focus after having taken the shot.

INTRODUCTION

The Lytro camera is a light-field or plenoptic camera, which means it captures not only the color and intensity of the light, but also the direction of each light ray. Knowing the direction of each light ray gives plenoptic cameras the ability to identify the exact location of an object, including its distance from the camera. The primary application for photography is to have a photo where you can change focus even after the shot is taken. Here is Lytro's promo video about it:

For the technical-minded here are some academic papers on the subject:

The Lytro camera came out in 2012, but at that time it cost as much as $399 (8GB) or $499 (16GB). I had been curious about it, but it was not a small amount of money for an entirely new concept. Moreover, the sensor was very small, compared to similarly-priced cameras. It became a niche camera. Since then, Lytro has produced a high-end model called the Illum with much higher image quality. As for the first generation Lytro camera, prices now have come down significantly, especially for refurbs. The first gen went on a special sale on Amazon a couple of months ago and I decided to get one.

APPLICATIONS

Before I discuss the camera itself, I'd like to discuss some ways that you can use the Lytro's capabilities:

1. Multilayered composition. The most typical way to use the Lytro is to have more than one point of interest at various distances. The camera allows the viewer to see each subject separately, somewhat like having two (or more) photos in one shot. In the shot below, the subject can either be the skeleton or the child, or both.

2. Hyperfocal shots. You can increase the depth of field and have everything (or almost everything) in focus without raising the ISO or using longer shutter speeds.

3. Unusually shallow depth of field. In bright sunlight for example, most cameras cannot have a wide open aperture because the required shutter speed would be too high (unless you use an ND filter).

5. Macros. The Lytro has a short working distance of around 2 inches (the Lytro Illum's minimum working distance is 0). In addition, you can increase the depth of field, without the need for focus stacking. Moreover, increasing the depth of field does not require raising the ISO or using longer shutter speeds. The shot below is of 12 point Times New Roman font, with the camera held around 1cm from the paper (note: it was handheld, so the sharpness is not as high as it ought to be).

6. Sports, kids or pets. Because it never misses focus, you can capture action shots of sports, kids or pets that will always be in focus. The practical limit is the shutter speed. In this regard, the first generation Lytro 1G's 1/250 shutter speed is not fast enough to freeze fast action. Moreover, the Lytro first generation can't use flash. However, the Lytro Illum has a maximum shutter speed of 1/4000 and has a hotshoe for external flash.

CAN'T YOU DO THE SAME THING IN PHOTOSHOP?

There are now many applications for the desktop and on mobile that are intended to simulate the Lytro's ability to refocus after-the-fact. The difference for Lytro is that the images contain the distance data therefore the depth of field in Lytro's images "should" look more realistic (see depth resolution and accuracy below).

BUILD QUALITY

The Lytro's body is aluminum and feels heavier than expected for its size. It looks sturdy and made with high quality components. However, the Lytro is not designed to be weatherproof.

Shooting rate: There is no continuous burst. You can take up to around 1 shot per second. After 5 shots, it slows down to around 1 shot per 2 seconds.

The resolution seems tiny but to be fair, it includes more information than a 1.2mp image from a normal camera because it includes depth information. Lytro argues that it is similar to having several sub-pictures embedded within it showing different focal points. By comparison, Raytrix, a company specializing in light field cameras for industrial applications, used an 8mb sensor to produce a 2mb image with its R5 camera (which had a cost of 3000 euros). Because a Lytro image contains more information than its nominal resolution would appear to suggest, Lytro describes its resolution in terms of "megarays" (millions of light rays captured). The Lytro first generation camera captures 11 megarays, while the Illum captures 40 megarays (4mp nominal resolution).

The images captured by the camera are square only.

USING THE CAMERA

The camera is designed to be simple to use. It has four modes: auto, manual, shutter priority, and ISO priority.

Auto

In the auto mode, you just slide the zoom (up to 5.5x), then press the shutter. That's it. In this mode, the camera shoots faster than typical point and shoot cameras because there's no need to focus.

Manual

In manual mode, the zoom has its full range (8x). To control exposure manually, you adjust the ISO and shutter speed. You swipe down the screen and tap either ISO or shutter speed, then slide the onscreen lever to choose the ISO or shutter speed. As you do this, there is an EV indicator. This mode is really manual, not shutter priority or ISO priority.

Shutter Priority and ISO Priority

When choosing the shutter speed or ISO, you can select "auto" to set the values to automatic for those exposure parameters. If shutter speed is on Auto, the Lytro effectively becomes ISO Priority, and if the ISO is on Auto, it is on Shutter Priority. You can't change the aperture but you can activate the ND filter (around 2 stops).

Other settings:

Auto exposure lock: like an iPhone, you can use AEL by tapping and holding on the part of the screen that you want to use for locking exposure. Unlike an iPhone, however, you can't adjust the auto exposure after it's locked.

Self-timer: either 2 seconds or 10 seconds.

Creative Mode: Creative Mode has two uses. First, it allows you to choose the primary focus. Second, Creative Mode also allows you to use a shorter minimum working distance (as little as around 1 cm from the lens at the widest focal length, instead of around 2 inches from the lens without Creative Mode).

Connectivity:

Lytro cameras have a built-in WiFi function that can send images to your phone. However, you need to update the firmware to v1.20 or later. You turn on the Wi-Fi in the Lytro, connect to the ad hoc network with your smartphone, and launch the Lytro app. Instructions here and here.

VIEWING IMAGES

Lytro images have several unique properties when being viewed:

They can be refocused.

The depth of field can be changed. In the Lytro Desktop application, you have full control over depth of field and can use different depths of field for different parts of the image (Focus Spread).

Perspective Shift: You can change the perspective to a small degree. Moving the perspective has the side effect of making it look three-dimensional.

The image can be exported as a 3D image.

The image can be exported as an animation (with changing focus, changing perspective, etc.).

These properties may or may not be available, depending on how you view the images:

1. Back of the camera: you can zoom and drag to scroll around the image, or you can zoom out to view 3x3 thumbnails. In terms of Lytro-specific features, you can refocus. The other features are not available.

2. Lytro Desktop (Windows, OS X). This free software allows you to view, edit and share images from your camera. All of the unique Lytro characteristics are available. The software is quite polished and looks somewhat like Lightroom. Beginning with v4.1, some editing options are available only for Illum and not the first generation (sharpening detail and masking, color channels).

3. Lytro Mobile (iOS only). This is a free app for your phone which allows you to view your own photos and those that have been uploaded by others to Lytro's online gallery.

Whether you're viewing others' photos or your own, the viewer allows you to refocus as well as adjust the depth of field (cleverly, you use two fingers to make a twisting motion, which changes the simulated aperture). In addition, when you tilt your phone, it adjusts the perspective, giving it a subtly three dimensional appearance (kind of like the parallax effect on some iPhone wallpapers).

4. The Lytro gallery (pictures.Lytro.com). This is a free online gallery for Lytro users. Lytro gives each user their own page (albums can be designated as public or unlisted). Once the images are uploaded to the site, the images can be seen on browsers running Adobe Flash (works best on Chrome and Firefox; Safari and Internet Explorer also supported). You can change focus, change perspective, zoom, or view a short animation.

5. 500px. Similar to the Lytro gallery.

6. Social media - interactive. From the Lytro gallery or 500px, you can share images to Facebook, Twitter, Google+ or Pinterest. On Facebook and Twitter, viewers don't have to install anything. They will be able to interact with the pictures immediately To interact with images on Google+ or Pinterest, viewers need to use a Chrome browser, and need to install an extension to the browser.

7. Social media - noninteractive. Using Lytro Desktop, the images can be exported as short video clips. From there, they can be shared on social media such as Facebook or Vine. The videos can also be exported as an animated GIF.

In my opinion, the overall image quality looks similar to an iPhone 4. Just like a smartphone, it has no highlight headroom and it won't do well in low light.

Limited highlight headroom:

Low light (ISO 800, 1/60, f/2):

That might sound disappointing but actually, it is ok for online viewing, which is what it is designed for. The main attraction of the images is not in their resolution, sharpness, color, or other conventional measures of image quality, but in their interactivity and composition.

DEPTH RESOLUTION AND ACCURACY

Because plenoptic cameras such as the Lytro record depth information, I think it is important to know the resolution and accuracy of the depth information. In this regard, the Lytro 1st generation seems suited only for casual use, because its depth information has mediocre resolution and accuracy. In terms of resolution, the Lytro 1G can only distinguish around 10 levels of depth, and most of those are within the nearest 3 feet or so.

Here is the depth map for the image above, showing 10 levels of depth, mostly within the first 3 feet or so:

Beyond 3 feet, the camera has difficulty distinguishing distance and can be hit-or-miss. If the subjects are far enough apart, the camera is generally accurate:

If the subjects are not very far apart, the camera can get confused. In the shot below, the 2nd child from the left was further from the camera yet looks like it is at the same focus depth as my kids.

Fortunately, if the depth map has an error, the Desktop application allows you to modify the depth map in an external graphic software.

ACCESSORIES

Fast charger. Lytro uses its USB port for both sending photos to your computer and charging the camera. Charging the camera via your computer's USB port can take as long as 8 hours. There is a fast charger available as an accessory, which reduces this to 5 hours.

Tripod adapter. This accessory allows you to use the Lytro with any tripod that uses the 1/4-20 mount. In theory, it is useful because you'll be able to use longer exposures at lower ISOs which will help improve the image quality. The build quality matches the camera and is made of aluminum and rubber. The problem is that the adapter doesn't tighten to the camera body and is a little loose. If you want it tight, you need to insert a folded piece of paper or some other shim.

EVALUATION

Overall, I would say a plenoptic camera does have interesting and unique photographic possibilities. The first generation Lytro is one way to try it out. It is easy to use, portable, and it provides a unique interactive way of presenting an image. The depth accuracy of the first generation model is somewhat spotty but should give you an idea if this is something worth looking into, in which case you might be interested in the Lytro Illum.